3 replies to this topic

[MSpencer]

The failure of normal cell differentiation patterns may explain cancer and senescent decline with aging, say researchers at the University of Arizona, the Santa Fe Institute, the University of Pennsylvania, and the Wistar Institute.

Darwinian natural selection and evolution is usually studied in populations of organisms, but it also applies to cellular populations; this is called "somatic" evolution. Such somatic evolution tends to reduce cooperation among cells, thus threatening the integrity of the organism.

In this study the authors proposed that a well-known pattern of ongoing cell differentiation in the mature tissues of animals functions to suppress somatic evolution, which is essential to the origin and sustainability of multicellular organisms.

The team, lead by Dr. John Pepper, tested this hypothesis using a computer simulation of cell population dynamics and evolution. The results were consistent with the hypothesis, suggesting that familiar patterns of ongoing cell differentiation were crucial to the evolution of multicellular animals, and remain crucial as a bodily defense against cancer.

Journal reference: Pepper JW, Sprouffske K, Maley CC (2007) Animal cell differentiation patterns suppress somatic evolution. PLoS Comput Biol 3(12): e250. doi:10.1371/journal.pcbi.0030250

(http://www.scienceda...71214094031.htm for a quick summary and for the full citation)

Seems rather interesting to me. It's another theory on the general cellular basis of aging and development of cancer (And is potentially a link between the two). It does make sense that over time, as with populations of organisms, the cells of multicellular organisms will be gradually selected for and against (Mostly for commonly dividing cells, I'm sure), resulting in decreased continued cooperativity. Not much we can do about it, but it could be the overall reason behind aging in the first place.
It's just one of those things you don't hear about now, but you'll hear about quite substantially in the next few years. This is potentially that link between the two (That one paper that opens peoples' eyes, attracting Brilliant Scientist A from Harvard who will snatch up the Nobel and the grants) that could result in, perhaps, regulatory drugs, or a new field of determining cellular cooperativity. It also should allow us to come up with a model for natural causes of death, and perhaps a terminal age beyond which humans cannot survive. It's also good to know what kills you, and how, so you can perhaps delay it.
Maybe it's the key to a longer life? It's just a thought, but I found it rather interesting, and it does tie into my research interests, so I'm subjecting everyone to it.

This will also be part of a perhaps weekly breakdown of science news which, for lack of a better place, will be part of my BNP... err... GNP blog (Just more of an overt response to the ridiculous, rude conservative propaganda which no doubt has preceded this post, which I will address a bit later). Since I prefer to write about my research and research interests, it'll mostly be about evolutionary and cell biology with a bit of genetics, but I'll try to survey most new scientific developments. It's tremendously interesting, really, and if you don't think so, well, you're a poor and decrepit human being.

Edited by MSpencer, 18 December 2007 - 07:50 AM.

[duke_Qa]

fascinating, i'm always for something that can potentially turn me into a immortal creature of great evil. as much as the average guy next door i bet.

Such somatic evolution tends to reduce cooperation among cells, thus threatening the integrity of the organism.

so basically, there is evolution in the cells themselves that makes the cells split further and further away from the original cells? sort of white people, black people, oriental people and so forth? i read somewhere recently that genetic differences between the different human divides are also becoming more and more distinct. after a few dozen generations or more, we might not be able to interbreed, having so different genetics that it won't be possible to get something out of it(don't think thats the case though, look at dogs, they can make the strangest things work).

[MSpencer]

Genetic differences are becoming more discrete, and have been getting that way for about the last 5,000 years. Nobody is quite sure why, but my money is on expanding population size, bottleneck events, and a sort of "intelligent" mate selection which isn't as advanced in other organisms. It may be a corrolary to natural selection that as the sophistication of the organism increases, the susceptibility to massive genetic changes over a short amount of time increases. I honestly don't know, it's one of my research interests, but alas, I don't study humans.

However, consider this:
With population size increasing, the law of large numbers takes effect and you have significant genetic drift over time. Genetic drift is essentially, the manifestation of statistical fluctuations in the genetics of a large (just not ridiculously tiny) population of individuals. This means that as time goes on, genes naturally drift apart and result in some changes in genetic composition. Essentially, it's the postulate that outside of any kind of natural selection, in a total vacuum, organisms would still exhibit genetic changes and evolutionary change, just not in response to a stimulus. It might seem abstract, but it's something to keep in mind in all models.
Humans also seem to exhibit some form of intelligent mate selection, whereby we not only act on the natural instincts to prohibit certain traits from moving on, but we also consciously try to avoid these traits, shunning people and reducing their chances of moving on to the next generation.
In a way, our intelligence speeds up natural selection in a sort of "out of environment" way. We're not being acted upon by natural selection anymore, in fact, it's now population selection, whereby we exhibit significant genetic differences because our populations are diversified, exhibit different preferences in people, and the sizes of those populations have increased.
It's an interesting field, but I work with... Drosophila...

so basically, there is evolution in the cells themselves that makes the cells split further and further away from the original cells?

Exactly. Just as in an environment, in multicellular organisms, productive cells are selected for since they're more likely to make it on to the next division.

[Hostile]

Never thought of cellular natural selection before, that's kinda a deep thought. Also I agree the vastness of human genetics in the last few thousand years is most likely because of the huge population increase.